Mount assembly for accessory gearbox of aircraft engine and associated method of assembly

Abstract

The relative position and orientation between an auxiliary gearbox and a casing of an aircraft engine can be set including engaging a localizing feature of the accessory gearbox with a localizing feature of the casing; and a load path between auxiliary gearbox can subsequently be defined including securing at least two brackets between the accessory gearbox and casing.

The invention claimed is: 
     
       1. An aircraft engine comprising:
 a casing extending along and around an axis, the casing having a first localizing feature and a shaft aperture; 
 an accessory gearbox having a second localizing feature and a driveshaft port, the second localizing feature engaged with the first localizing feature; 
 a driveshaft extending radially relative the axis, through the shaft aperture, the driveshaft engaged with the driveshaft port, a front and a rear defined in opposite directions from the driveshaft along the axis, a left side and a right side defined in opposite directions from the driveshaft in a lateral orientation transversal to the axis; 
 a first bracket having a proximal end secured to the casing on a first one of the left side and right side and a first one of the front and the rear, and a distal end having a first clearance hole, the first bracket fastened to the accessory gearbox by a first fastener having a first shaft extending through the first clearance hole, a first clearance being defined by a difference between a size of the first clearance hole and a size of the first shaft, the first clearance providing a degree of freedom for movement of the first shaft in the first clearance hole, and 
 a second bracket having a proximal end secured to the casing on the first one of the left side and right side and a second one of the front and the rear opposite the first one of the front and the rear, and a distal end having a second clearance hole, the second bracket fastened to the accessory gearbox by a second fastener having a second shaft extending through the second clearance hole, a second clearance being defined by a difference between a size of the second clearance hole and a size of the second shaft, the second clearance providing a degree of freedom for movement of the second shaft in the second clearance hole; 
 wherein the casing has a sequence of at least three sections each extending circumferentially around the axis, including a first section secured to a second section at a first structural annular flange arrangement, a third section secured to the second section at a second structural annular flange arrangement, the second section having the shaft aperture and the first localizing feature, the proximal end of the first bracket secured to the first structural annular flange arrangement, the proximal end of the second bracket secured to the second structural annular flange arrangement, the first structural annular flange arrangement and the second structural flange arrangement extending circumferentially around the axis 
 wherein a relative position between the distal end of the first bracket and the distal end of the second bracket is determined from an assembly tolerance stackup set by the engagement between the first localizing feature and the second localizing feature, the first clearance and the second clearance configured to accommodate the assembly tolerance stackup. 
 
     
     
       2. The aircraft engine of  claim 1  wherein the proximal end of the first bracket has a third clearance hole, the first bracket fastened to the casing through the third clearance hole, the third clearance hole being defined in a different orientation than the first clearance hole, the proximal end of the second bracket has a fourth clearance hole, the second bracket fastened to the casing through the fourth clearance hole, the fourth clearance hole being defined in a different orientation than the second clearance hole. 
     
     
       3. The aircraft engine of  claim 1  wherein the casing has a top and a bottom defined in opposite directions from the axis along a height orientation, the height orientation being transversal to the axis and to the lateral orientation, the accessory gearbox being at the top of the casing. 
     
     
       4. The aircraft engine of  claim 1  further comprising a structural web extending axially between the first bracket and second bracket, the structural web being secured to both the first bracket and the second bracket. 
     
     
       5. The aircraft engine of  claim 1  wherein the first bracket and the second bracket each have a body extending both radially and circumferentially relative the axis. 
     
     
       6. The aircraft engine of  claim 5  wherein the distal end of the first bracket and the distal end of the second bracket each have a corresponding flange extending circumferentially and axially relative to the axis, said first clearance hole and said second clearance hole being defined through said corresponding flange. 
     
     
       7. The aircraft engine of  claim 1  further comprising a third bracket having a proximal end secured to the casing on a second one of the left side and the right side opposite the first one of the left side and the right side, and a distal end having a third clearance hole, the third bracket fastened to the accessory gearbox via the third clearance hole. 
     
     
       8. The aircraft engine of  claim 7  wherein a load path between the auxiliary gearbox and the casing is mainly defined via the brackets. 
     
     
       9. The aircraft engine of  claim 1  wherein the first localizing feature has a peripheral flange and a tip forming a length-wise delimitation to the peripheral flange, the second localizing feature has a male member and an axial seat, the male member slidable along the peripheral flange until the tip of the peripheral flange abuts against the seat, and the shaft aperture is formed internally to a periphery of the peripheral flange. 
     
     
       10. The aircraft engine of  claim 9  wherein the peripheral flange is circular in a plane transversal to an orientation of a length of the driveshaft, wherein the first localizing feature and the second localizing feature further comprise a clocking feature configured for setting the relative circumferential orientation of the male member within the peripheral flange. 
     
     
       11. The aircraft engine of  claim 1  wherein the axis is a main axis, the driveshaft extending along a driveshaft axis, the first localizing feature and the second localizing feature engaged along the driveshaft axis, the engagement of the first localizing feature and of the second localizing feature setting a relative position and orientation of the accessory gearbox relative the casing in a plane normal to the driveshaft axis. 
     
     
       12. The aircraft engine of  claim 11  wherein the first localizing feature has a peripheral flange, the second localising feature has a male member, one of the peripheral flange and the male member has a tip, the other one of the peripheral flange and the male member has a seat, the male member slidable in the orientation of the driveshaft axis along the peripheral flange until the tip abuts the seat. 
     
     
       13. The aircraft engine of  claim 1  wherein the first bracket forms part of a load path between the accessory gearbox and the casing; the second bracket forms part of the load path, the load path decoupled from said engagement of the first localizing feature and of the second localizing feature. 
     
     
       14. The aircraft engine of  claim 1  wherein both the first bracket and the second bracket are of a unibody construction, formed of a single component without any articulations.